1890.] NATURAL SCIENCES OF PHILADELPHIA. 185 



Fossil. Recent. 



Transverse diameter .... 16mm. 10mm. 



Fore and aft do 11 mm. ' 8mm. 



It perliaps pertains to the same species as the fragment of a man- 

 dible from Nicaragua, referred to Hydrochoerus rohustus (Proc. 

 1886, 275). 



Since the description of the latter, I have seen the notice of a 

 species, H. magnus, indicated by the ramus of a mandible found in 

 Buenos Ayres, S. A. (Gervais and Ameghino, Mammif Fossiles de 

 I'Amerique du Sud, Paris, 1880, 45). The size of the former 

 apj)ears to accord with that of the latter species, and they are 

 perhaps the same. The antero-posterior diameter of the first lower 

 molar attributed to H. rohustus is 25mm. Ameghino gives as the 

 same diameter of the second lower molar of H. magnus, 26mm. (Bol. 

 Acad. Nac. Ciencias, Buenos Ayres 1883, 273). In the recent 

 Capybara, the fore and aft diameter of the first and second lower 

 molars is nearly the same ; so that the measurement of the correspond- 

 ing teeth in the two fossils would indicate animals of the same size, 

 and it may be suspected, the same species. 



The following were elected members : — 



Alfred G. Baker, Charles Piatt, John Cadwalader, Clement A. 

 Oi'iscom, Charles P. Hayes, James iVIacAllister, Thomas Miles, 

 John C. Garland, Annesley R. Govett, David Milne and Caleb J. 

 Milne. 



The following were ordered to be printed : — 



